Large scale integration (LSI) become smaller and have higher densities, and this in turn increases resistances and capacitances of wirings in the circuits, resulting in transmission delays. Accordingly, optical interconnect technology attracts attention.
A semiconductor laser having a micro ring resonator structure has been known as a small light source for the optical interconnect technology. In this kind of semiconductor laser, however, the intensity distribution of laser-oscillated light circulating in a ring is unevenly distributed in proximity to sidewalls of the ring.
As a result, the following problems occur. Light loss increases due to scattering of light caused by roughness of the sidewalls. Carrier loss increases due to surface recombination and surface trap level caused by damage of the sidewalls.
A semiconductor laser is made into a thin film so that the semiconductor laser is mounted on a large scale integration. As a result, there is a problem in that an overlap increases between an internal light intensity distribution and a high density contact layer/an electrode, which increases the light loss caused by the high density contact layer and the electrode.
Therefore, there is a problem in that a sufficient laser oscillation characteristic cannot be obtained.